Recently, a small-sized projection projector using the MEMS and the semiconductor laser light source has been spreading. Examples of the background art of this technical field includes JP 2006-343397 A (Patent Document 1) and JP H5-224166 A (Patent Document 2). Patent Document 1 and Patent Document 2 disclose a projector that performs scanning in horizontal and vertical directions with biaxial MEMS mirror or scanner and modulates a laser light source to project an image. In the small-sized projection projector using a semiconductor laser as described above, amount of light-forward current characteristics of the semiconductor laser, which is used, vary due to a temperature. Therefore, there is known a problem that white balance of a display screen varies.
In addition, Patent Document 2 discloses a grayscale correcting device that performs optical modulation with an optical modulator by extrapolating a test signal during a flyback period that is a non-video display period, stores actual grayscale characteristics calculated by a microprocessor and ideal characteristics in a storage device through feedback, and automatically performs grayscale correction during a normal operation.